Multi-functional portable devices, such as: personal digital assistant (PDA), portable communication products, etc., have already become indispensable tools in our daily lives. However, in order to extend the convenience and the function of portable device, the resetting action of the IC arranged in the extensive accessory must be accurately completed when the relationship with the matched separable extensive accessory is changed (i.e., pulling out/inserting in), such that the entire system may operate normally.
When the separable extensive accessory processes the pulling-out/inserting-in actions to the portable device, there are two kinds of resetting manner to the IC arranged in the extensive accessory. First kind: by a resetting signal provided by the portable device, the IC is reset through the state transition of the signal. FIG. 1 is an illustration for the embodiment according to this kind of prior art. In FIG. 1, the portable device 10 has a resetting device 40, which may provide a resetting signal to the IC 30 in the separable extensive accessory 20 to complete the resetting action of the IC 30. However, since it has to additionally arrange a resetting device 40 in the portable device 10, so it reduces the available space and resource of the portable device 10.
FIG. 2A is an illustration of the embodiment of the second kind of prior art. It is possible to arrange a RC circuit 50 in the separable extensive accessory. The capacitance C is short-circuited to ground when the switch of the power source VCC is opened, such that an action to pull-down a signal from high to low is generated. By further applying a charging action to the capacitance C by the power source VCC, the signal is raised to high to end the resetting action of the IC 30. However, when using this kind of prior art, it must be sure that the power source VCC is in closed state and the capacitance C has already discharged completely before the separable extensive accessory 20 is inserted into the portable device 10. In addition, when the pulling-out/inserting-in actions between the separable extensive accessory 20 and the portable device 10 are executed continuously during short period, a mistake of the separable extensive accessory 20 may be occurred to cause the system unable to operate normally because of the problems of stability and transient state. FIG. 2B is a wave diagram of the resetting signal generated by the resetting device of FIG. 2A.
Therefore, aiming to the shortcomings of above prior arts, a resetting device for separable extensive accessory is proposed; when the connecting relationship between the separable extensive accessory and the portable device is changed, the resetting action of the IC arranged in the separable extensive accessory may be completed, and this is the emphasis of the present invention.